156 Proceedings of the Royal Irish Academy. 



action of stainioiis chloriile upon the iiitio-compouinl in acetic acid solution 

 o-ave 2-aniino-stilbene, which was ihen diazotized in alcoliol solution with 

 aniyl nitrite, and the product shaken up with copper bronze, yielding stilbene. 

 •The following scheme represents the results achieved : — 



2.4-Dinitrostilbene -^ 2-nitro-4-aniinostilLene -^ 2-nitrostilbcne 

 -^ 2-aniinostilbene -> stilbene. 



As the above results indicate, ammonium sulphide first attacks tLe 

 para-nitro group in 2-4-diuitrostilbeue. Stannous chloride, however, is found 

 to attack the ortho-nitro-group first, leaving the para-group intact. For 

 instance, when the dinitrostilbene is reduced in acetic acid solution with one 

 molecular proportion of stannous chloride 4-nitro-2-aminostilbene results. 

 Tiiiele aud Escales {loc. cit.) acted upon the dinitrostilbene in the cold with a 

 cold solution of stannous chloride in hj-drochloric acid — acetic acid. 

 Employing this method, however, the reaction is of long duration (4-6 hours), 

 but an equally large yield may be obtained in 5-10 minutes by carrying out 

 the reduction at a somewhat higher temperature. 



When two molecular proportions of stannous chloride were used, 2-A- 

 dinitrostilbene was reduced to 2-4-diaminostilbeue (compare Thiele and 

 Escales, loc. cit.). 



The sulphate of 2-amino-4-nitrostilbeue was readily converted into the 

 corresponding diazouium salt by diazotization in alcohol solution with amyl 

 nitrite. The product on being shaken with copper bronze in the presence of 

 alcohol was reduced to 4-nitrostilbene, which was identifi.ed by comparison 

 with the synthetic compound produced by the condensation of ^^-nitrophenyl- 

 acetic acid aud benzaldehyde (Pfeifier and Sergiewskaja, Ber. d. Dtsch. Chem. 

 Ges., xliv, 1911, p. 1109). 



Stannous chloride reduces 4-nitrostilbeDe to its amino-derivativc. 



2'4-Diuitrotolueue was also condensed in the usual manner with auisal- 

 dehyde, giving 2-4-dinitro-4'-methoxystilbene (Pfeifi'er, Ber. d. Dtsch. Chem. 

 Ges., xlviii, 191.5, p. 1804), on partial reduction of which, by means of 

 stannous chloride, J-nitro-'<!-amino-4'-methoxystilbene was produced. The 

 latter substance was observed to exist in two chromoisomeric modifications, 

 one yellow, the other red (compare Gulliuane, Journ. Chem. Soc, cxxiii, 192.3, 

 p. 2Qoo). It separated from acetone solution in bright-red prisms, while on 

 pouring a cold solution in glacial acetic acid into wal€r, small orange-yellow 

 needles were obtained. The red form is tlie stable one ; the yellow compound 

 on being heated turns red at about lOO'C, and melts at the same temperature 

 as the red modification. 



The above result is quite in accord with Pfeiffer's views on the chromo- 

 isouierisni of uitromethoxystUbenes (Ber. d. Dtsch. Chem. Ges., li, 1918, 



